NullPointerException when trying Interpret parser...

[oyse]

For at least one file a NullPointerException is thrown when trying to do Interpret parser...

java.lang.NullPointerException
    at org.antlr.v4.runtime.DiagnosticErrorListener.getConflictingAlts(DiagnosticErrorListener.java:175)
    at org.antlr.works.editor.grammar.debugger.StatisticsParserErrorListener.reportAmbiguity(StatisticsParserErrorListener.java:30)
    at org.antlr.v4.runtime.ProxyParserErrorListener.reportAmbiguity(ProxyParserErrorListener.java:55)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.reportAmbiguity(ParserATNSimulator.java:2365)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.execATN(ParserATNSimulator.java:812)
    at org.antlr.works.editor.grammar.debugger.StatisticsParserATNSimulator.execATN(StatisticsParserATNSimulator.java:144)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.execDFA(ParserATNSimulator.java:556)
    at org.antlr.works.editor.grammar.debugger.StatisticsParserATNSimulator.execDFA(StatisticsParserATNSimulator.java:107)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.adaptivePredict(ParserATNSimulator.java:423)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.adaptivePredict(ParserATNSimulator.java:373)
    at org.antlr.works.editor.grammar.debugger.StatisticsParserATNSimulator.adaptivePredict(StatisticsParserATNSimulator.java:99)
    at org.antlr.v4.runtime.ParserInterpreter.visitState(ParserInterpreter.java:185)
    at org.antlr.works.editor.grammar.debugger.ParserDebuggerReferenceAnchorsParserTask$TracingParserInterpreter.visitState(ParserDebuggerReferenceAnchorsParserTask.java:137)
    at org.antlr.v4.runtime.ParserInterpreter.parse(ParserInterpreter.java:157)
    at org.antlr.works.editor.grammar.debugger.ParserDebuggerReferenceAnchorsParserTask.parse(ParserDebuggerReferenceAnchorsParserTask.java:115)
    at org.antlr.netbeans.parsing.spi.impl.ParserTaskManagerImpl$UpdateDataCallable.callImpl(ParserTaskManagerImpl.java:662)
    at org.antlr.netbeans.parsing.spi.impl.ParserTaskManagerImpl$UpdateDataCallable.callImpl(ParserTaskManagerImpl.java:618)
[catch] at org.antlr.netbeans.parsing.spi.impl.ParserTaskManagerImpl$UpdateCallable.call(ParserTaskManagerImpl.java:607)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
    at org.antlr.netbeans.parsing.spi.impl.ParserTaskManagerImpl$PriorityInsertionRunnableScheduledFuture.run(ParserTaskManagerImpl.java:821)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

[sharwell]

Can you include a sample grammar and input file which demonstrates this problem?

[amirico]

It happens to me as well now. Even with the basic grammar provided in the very first example on "The definitive ANTLR 4 reference. (I am working on a HP COMPAQ Evo N619c. Before I moved to this laptop it never happened.)

This is the exception -

Exception in thread "main" java.lang.NullPointerException at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) at org.antlr.v4.runtime.misc.TestRig.process(TestRig.java:157) at org.antlr.v4.runtime.misc.TestRig.main(TestRig.java:142)